Table of Contents

Event Filter (S800 Filter)

The trigger bits words indicates which bits were set during the event. The encoding of the bits is the following:

In this section, each 16-bit word sent by the Filter is described by a 16×3-table diagram. The first row includes the value, either in decimal or hexadecimal format, or a descriptive note. The second row shows the value in binary (“X”s are used to describe arbitrary values that vary from event to event). The last row shows the bit number.

Time-stamp packet

The timestamp is encoded in the XLMV72 time-stamp module for each event as a 64-bit word. The Event Filter parses it as a set of four consecutive 16-bit words.

Packet Length (self-inclusive)

5

0

0

0

0

0

0

0

0

0

0

0

0

0

1

0

1

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

Packet Tag

0x5803

0

1

0

1

1

0

0

0

0

0

0

0

0

0

1

1

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

First 16-bit time-stamp word

First 16-bits “chunk” of time-stamp

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

Second 16-bit time-stamp word

Second 16-bits “chunk” of time-stamp

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

Third 16-bit time-stamp word

Third 16-bits “chunk” of time-stamp

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

Fourth 16-bit time-stamp word

Fourth 16-bits “chunk” of time-stamp

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

Event-number packet

The event-number is given by the VMUSB scaler channels as a 48-bit word coded in two 32-bit words. The Event Filter parses it and re-formats it as a three 16-bit words.

Packet Length (self-inclusive)

4

0

0

0

0

0

0

0

0

0

0

0

0

0

1

0

0

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

Packet Tag

0x5804

0

1

0

1

1

0

0

0

0

0

0

0

0

1

0

0

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

First 16-bit event-number word

First 16-bits “chunk” of event-number

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

Second 16-bit event-number word

Second 16-bits “chunk” of event-number

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

Third 16-bit event-number word

Third 16-bits “chunk” of event-number

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

Trigger packet

The trigger packet includes a bit-pattern word (encoded by the ULM trigger module), with information about what sources triggered the event, and their corresponding time from the Phillips 7186 TDC.

Packet Length (self-inclusive)

A number from 2 to 7

0

0

0

0

0

0

0

0

0

0

0

0

0

X

X

X

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

Packet Tag

0x5801

0

1

0

1

1

0

0

0

0

0

0

0

0

0

0

1

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

Trigger pattern

Bit pattern

0

0

0

0

0

0

0

0

0

0

0

X

X

X

X

X

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

the encoding of the active bits is given by the following table:

Bit

Source

0

S800 (from E1 up)

1

Coincidence

2

External 1

3

External 2

4

Secondary (e.g. GRETINA)

Trigger time

The time of each trigger source (except for “coincidences”) is given by a word that look like:

Ch

time

0

0

0

X

X

X

X

X

X

X

X

X

X

X

X

X

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

there can be up to four time words (depending on whether time is greater than 0), one for each channel. The channel number Ch is given by:

The time-of-flight information for each channel is coded in words that look like:

Ch

time

0

0

0

X

X

X

X

X

X

X

X

X

X

X

X

X

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

Up to eight of these words can be present (depending on wheter time is greater than 0): six from the Phillips TDC, and two from the XFP-FP and OBJ-FP TACs. The channel number Ch is given by:

Ch

Source

6

Phillips TDC time from the A1900 IM2 north scintillator (optional)

7

Phillips TDC time from the A1900 IM2 south scintillator (optional)

12

Phillips TDC time from the RF

13

Phillips TDC time from the OBJ scintillator

14

Phillips TDC time from the XFP scintillator

15

Phillips TDC time from the LaBr (optional)

4

XFP-FP time-of-flight from TAC

5

OBJ-FP time-of-flight from TAC

Note that the time values from the Phillips TDC are subtracted by SpecTcl to the time from the S800 trigger E1 up (encoded in the trigger packet) in order to calculate the corresponding time-of-flight. On the other hand, the times from the TACs (Ch 4 and 5) correspond to actual time-of-flight values.

Scintillator packet

The scintillator packet includes the energy (encoded in the FERA LeCroy module) and time (encoded in the Phillips TDC) of the S800 FP scintillator signals. In the original configuration, there were 3 scintillators (E1, E2, and E3) which were later reduced to just one (E1) after the installation of the Hodoscope.

Packet Length (self-inclusive)

A number from 4 to 8

0

0

0

0

0

0

0

0

0

0

0

0

X

X

X

X

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

Packet Tag

0x5810

0

1

0

1

1

0

0

0

0

0

0

1

0

0

0

0

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

Energy and time values

The energy (from the FERA module) and time (from the Phillips TDC) are given by two consecutive words:

Ch

energy

0

0

0

X

0

X

X

X

X

X

X

X

X

X

X

X

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

Ch

time

0

0

0

X

X

X

X

X

X

X

X

X

X

X

X

X

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

These words are sent by the Filter as long as energy is greater than 0 or Ch equals 2. The channel assignment given by the Filter is:

This word is reserved for a global threshold; it is no longer used, so it is set to 0

Samples sub-packets

The Filter sends a series of sample sub-packets. Each sub-packet consists of two parts. The first part includes one 16-bit word with information about the sample and channel numbers:

control bit

sample

channel

1

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

where channel is a number between 0 and 63, and refers to a group of four pads. The second part includes up to four consecutive 16-bit words, each with a pad energy greater than 0:

control bit

empty

connector

energy

0

0

0

0

X

X

X

X

X

X

X

X

X

X

X

X

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

The connector number is related to the pad number (pad) according to: pad = channel + connector x 64 (where connector ranges from 0 to 3, and channel is given by the first word of the sample sub-packet). Note that the Filter processes information from connectors with energies greater than 0.

TPPACs packet

The Filter parses and re-formats information from the Tracking PPACs encoded in the XLM72 TPPACs module. The new packet includes both TPPACs; its structure is very similar to that from the CRDCs.

Packet Length (self-inclusive)

A number from 5 to 325

0

0

0

0

0

0

0

X

X

X

X

X

X

X

X

X

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

Packet Tag

0x5870

0

1

0

1

1

0

0

0

0

1

1

1

0

0

0

0

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

TPPAC Sub-packet “Raw” Length (self-inclusive)

A number from 3 to 323

0

0

0

0

0

0

0

X

X

X

X

X

X

X

X

X

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

TPPAC Sub-packet “Raw” Tag

0x5871

0

1

0

1

1

0

0

0

0

1

1

1

0

0

0

1

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

Global threshold

0x0000

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

This word is reserved for a global threshold; it is no longer used, so it is set to 0

Samples sub-packets

The Filter sends a series of sample sub-packets. Each sub-packet consists of two parts. The first part includes one 16-bit word with information about the sample and channel numbers:

control bit

sample

channel

1

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

where channel is a number between 0 and 63, and refers to a group of four pads. The second part includes up to four consecutive 16-bit words, each with a pad energy greater than 0:

control bit

empty

connector

energy

0

0

0

0

X

X

X

X

X

X

X

X

X

X

X

X

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

The connector number is defined between 0 and 3, and it is related to the pad number (pad). The value 0 refers to the first 64 pads, and correspond to the strips in the dispersive direction of the first TPPAC. The value 1 is for pads between 63 and 127, and includes the strips in the non-dispersive direction of the first TPPAC. The value 2 corresponds to pads between 128 and 191, which are associated to the strips in the dispersive direction of the second TPPAC. Finally, the value 3 corresponds to pads between 191 to 256, and covers the strips in the non-dispersive direction of the second TPPAC.

The value of pad is given by index + connector x 64, where index is depends on the value of channel and connector according to the table below, where the second column shows the index values for connector=0 or 2, and the third column corresponds to the index values for connector=1 or 3:

Every time value encoded in the MTDC is sent by the Filter as a series of two 16-bit words: the first one provides information about the MTDC channel and the hit number; the second one gives the time value for that channel-hit. In the current version (Oct. 2015), the Filter processes up to 32 hits per channel. This value can be increased if necessary.